Method of controlling the temperature of a reaction carried out in a fluidised bed reactor

Abstract

Method of controlling the temperatures of an exothermic process carried out in a suspension of solids in a reactor system formed by a wind box (2), a vertical riser (5), which is essentially not cooled, a particle separator (6), at least one set of recycling channels (9), which are not cooled, and at least one cooled set of recycling channels (12). According to the invention, the flow of solids travelling through the recycling channel (9), which is no cooled, as adjusted based on the temperature difference (T2-T1) between the upper and lower parts of a riser (5), which is not cooled, and the flow of solids travelling through the heat exchanger (12) is adjusted based on the temperature (T1) of the lower part or the temperature (T2) of the upper part of the riser tube. The control of the riser temperature is thus exclusively based on the regenerative heat transfer of the solids returned from the heat exchangers. In order for the solids returning from the heat exchanger not to create too great a temperature difference in the riser tube, solids that are not cooled are also returned to the lower part of the riser chamber in accordance with the set point control of the temperature difference of the riser tube. As all the temperatures of the thermally insulated riser tube are between the temperatures of its lower and upper parts, a perfect temperature control of the reactor is achieved by means of the simple method according to the invention.

What is claimed is:  
     
       1. A method of controlling the temperatures of an exothermic process carried out in a suspension of solids in a reactor system formed by a wind box ( 2 ), a vertical riser ( 5 ), which is essentially not cooled, a particle separator ( 6 ), at least one set of recycling channels ( 9 ), which are not cooled, and at least one cooled set of recycling channels ( 12 ) with a heat exchanger, characterized by adjusting the flow of solids travelling through the recycling channel ( 9 ), which is not cooled, based on the temperature difference (T 2 −T 1 ) between the upper and lower parts of a riser ( 5 ), which is not cooled, and by adjusting the flow of solids travelling through the heat exchanger ( 12 ) based on the temperature (T 1 ) of the lower part or the temperature (T 2 ) of the upper part of the riser tube. 
     
     
       2. The method according to  claim 1 , characterized in that the solids circulations of the other recycling channels parallel to the recycling channels ( 9 ), ( 12 ) are controlled as free variables based on a process quantity characteristic for the function of the respective recycling channel. 
     
     
       3. The method according to  claim 1  or  claim 2 , characterized by directing the flow of solids through the recycle channel ( 9 ), which is not cooled, by means of an actuator ( 10 ) fitted at the upper part of the channel. 
     
     
       4. The method according to  claim 1  or  claim 2 , characterized by directing the flow of solids through other recycle channels than the one ( 9 ), which is not cooled, by means of an actuator ( 11 ), which is fitted at the lower end of the recycle channel. 
     
     
       5. The method according to  claim 1 , characterized by transferring heat to two or several heat-receiving flows in the same recycle channel ( 12 ). 
     
     
       6. The method according to  claim 1 , characterized in that solids are recycled through the recycling channel ( 9 ), which is not cooled, in an unpacked state. 
     
     
       7. The method according to  claim 1 , characterized in that solids are recycled through the cooled recycling channel ( 12 ) in a packed state. 
     
     
       8. The method according to  claim 1 , characterized in that the exothermic reaction is carried out in a circulating bed reactor, which comprises a wind box ( 2 ) with a gas feed nozzle ( 1 ), a vertical, essentially not cooled, riser ( 5 ) connected with the wind box, generally having a vertical central axis and having a lower portion ( 4 ), which is equipped with a feed nozzle ( 3 ) for solid matter, a particle separator ( 6 ) fitted on the riser at the upper portion thereof for separating particles from the flow of the solids suspension in the riser and having an outlet means ( 7 ) for the separated particles, and recycling channels ( 9 ;  12 ) connected with the outlet means of the particle separator, which channels can be used for recycling at least a part of the solid matter to the lower portion of the riser, whereby the recycling channels comprise at least one set of recycling channels ( 9 ), which are not cooled, and at least one cooled set of recycling channels ( 12 ). 
     
     
       9. The method according to  claim 1  characterized in that the exothermic reaction is a combustion reaction or cracking reaction.